The fission fragment angular distributions for the system12C +232Th have been measured in the energy range 0.97 1.05, they are abnormally large at lower energies. This is also true for the existing measurements of16O and19F +232Th systems. Since for this system pre-equilibrium fission contributions are not expected, this anomaly indicates strong channel coupling effects leading to an increase in 〈l2〉 at sub-barrier energies.